Splits a string into an array of strings, and returns it. By default, empty
leading fields are preserved, and empty trailing ones are deleted.

If not in list context, returns the number of fields found and splits into
the @_ array. (In list context, you can force the split into @_ by using ?? as the pattern delimiters, but it still returns the list value.) The use of
implicit split to @_ is deprecated, however, because it clobbers your subroutine arguments.

If
EXPR is omitted, splits the $_ string. If
PATTERN is also omitted, splits on whitespace (after skipping any leading whitespace). Anything matching
PATTERN is taken to be a delimiter separating the fields. (Note that the delimiter may be longer than one character.)

If
LIMIT is specified and positive, splits into no more than that many fields (though it may split into fewer). If
LIMIT is unspecified or zero, trailing null fields are stripped (which potential users of
pop() would do well to remember). If
LIMIT is negative, it is treated as if an arbitrarily large
LIMIT had been specified.

A pattern matching the null string (not to be confused
with a null pattern //, which is just one member of the set of patterns matching a null string) will split the value of
EXPR into separate characters at each point it matches that way. For example:

print join(':', split(/ */, 'hi there'));

produces the output 'h:i:t:h:e:r:e'.

The
LIMIT parameter can be used to split a line partially

($login, $passwd, $remainder) = split(/:/, $_, 3);

When assigning to a list, if
LIMIT is omitted, Perl supplies a
LIMIT one larger than the number of variables in the list, to avoid unnecessary work. For the list above
LIMIT would have been 4 by default. In time critical applications it behooves you not to split into more fields than you really need.

If the
PATTERN contains parentheses, additional array
elements are created from each matching substring in the delimiter.

split(/([,-])/, "1-10,20", 3);

produces the list value

(1, '-', 10, ',', 20)

If you had the entire header of a normal Unix email message in $header, you could split it up into fields and their values this way:

The pattern /PATTERN/ may be replaced with an expression to specify patterns that vary at
runtime. (To do runtime compilation only once, use /$variable/o.)

As a special case, specifying a
PATTERN of space (' ') will split on white space just as split() with no arguments does. Thus, split(' ') can be used to emulate awk's default behavior, whereas split(/ /)
will give you as many null initial fields as there are leading spaces.
Asplit() on /s+/ is like a split(' ') except that any leading whitespace produces a null first field.
Asplit() with no arguments really does a split(' ', $_) internally.